Electrosurgical treatment of atrial fibrillation with a new intraoperative radiofrequency ablation catheter

Surgery for Atrial Fibrillation: Selecting the Procedure for the Patient

This manuscript aims to review the current knowledge in the field of surgical ablation of atrial fibrillation (AF), including a brief discussion regarding the standard Maze procedure, its variants, minimally invasive thoracoscopic procedures and hybrid treatments, which briefly summarizes the advantages and differences between each technique. The rationale for the surgical approach of the left atrial appendage, its different techniques and complications will also be briefly covered. To conclude, the current Expert Consensus recommendations will be reviewed and an algorithm for the surgical management of the patient with AF, suggesting which technique applies better to which patient, under specific settings, will also be proposed.

The effect of preoperative atrial fibrillation on survival following mitral valve repair for degenerative mitral regurgitation

OBJECTIVE

There is conflicting evidence with regard to the impact of preoperative atrial fibrillation (AF) on the post mitral valve (MV) repair on the early and late outcome.

METHODS

A total of 349 patients undergoing various MV repair procedures for degenerative mitral regurgitation (MR) between 1997 and 2003 were studied. Preoperatively, 152 (44%) of these patients were in AF and 197 (56%) patients were in sinus rhythm (SR). The clinical features and the outcome in these two cohorts of patients were compared.

RESULTS

The patients in the AF group were older than their counterparts in the SR group (66+/-7 vs 62+/-9 years) (p=0.01), had a higher mean NYHA class score (2.4+/-0.6 vs 2.2+/-0.7) (p=0.04) and were more likely to have impaired left ventricular function (60% vs 36%) (p<0.0001). A similar proportion of patients in the AF (38%) and SR (30%) groups had additional cardiac surgical procedures (p=0.12). Operative mortality was 3.9% in AF group versus 0.5% in SR group (p=0.04), and operative morbidity was 27% versus 17%, respectively (p=0.03). At latest follow up, 4% of patients that were in SR preoperatively developed AF; conversely, 2% of the patients in the AF group converted to SR. The rates of recurrent grade II or III MR (4% vs 5%) (p=0.8) and MV re-operation (2.6% vs 2.5%) (p=1.0) were similar in the AF and SR groups. Kaplan-Meier survival at 7 years was 75+/-6% versus 90+/-3% (p=0.005). On Cox proportional hazards regression model, impaired LV function [(p=0.02), hazard ratio 0.25 (95% confidence intervals (C.I.) 0.078-0.84)] and AF [(p=0.03), hazard ratio 2.70 (95% C.I. 1.09-6.68)] were significant adverse predictors of survival.

CONCLUSIONS

This study shows that in patients undergoing MV repair for degenerative MR, preoperative AF has a major negative impact on the early and late survival.

Atrial Ablation for the Surgical Treatment of Atrial Fibrillation:. Principles and Limitations

This article reviews the development of procedures designed to eradicate atrial fibrillation by creating nonincisional lesions in the atria. Percutaneous interventional and surgical data are reviewed and analyzed. A major limitation of the surgical approaches, which utilize a variety of energy sources, appears to be the difficulty in achieving transmurality in all patients. A second limitation is related to a poor understanding of the underlying mechanisms of atrial fibrillation, and the consequent uncertainty as to the ideal lesion configurations necessary to counter these mechanisms. The article also discusses the various types of clinical atrial fibrillation, and discusses the differences between endocardial and epicardial application of thermal energy sources. Finally, atrial contractility is addressed, and the authors conclude that the ideal procedure will achieve a balance between conversion to normal sinus rhythm and the preservation of atrial contractility.

Cardiac Surgery for Arrhythmias

Cardiac arrhythmia surgery was initiated in 1968 with the first successful division of an accessory AV connection for the Wolff-Parkinson-White Syndrome. Subsequent surgical procedures included the left atrial isolation procedure and the right atrial isolation procedure for automatic atrial tachycardias, discrete cryosurgery of the AV node for AV nodal reentry tachycardia, the atrial transection procedure, corridor procedure and Maze procedure for atrial fibrillation, the right ventricular disconnection procedure for arrhythmogenic right ventricular tachycardia, the encircling endocardial ventriculotomy, subendocardial resection procedure, endocardial cryoablation, the Jatene procedure, and the Dor procedure for ischemic ventricular tachycardia. Because of monumental strides in the treatment of most refractory arrhythmias by endocardial catheter techniques during the past decade, the only remaining viable surgical procedures for cardiac arrhythmias are the Maze procedure for atrial fibrillation and the Dor procedure for ischemic ventricular tachycardia. Nevertheless, the 25-30 years of intense activity in the field of cardiac arrhythmia surgery provided the essential foundation for the development of these catheter techniques and represent one of the most exciting and productive eras in the history of medicine. In one short professional career, we have witnessed the birth of arrhythmia surgery, its adolescence as an "esoteric" specialty, its prime as an enlightening yet exhausting period, and finally its waning years as a source of knowledge and wisdom on which better methods of treatment have been founded. One could hardly ask for a more rewarding experience.

Cardiac Surgery for Arrhythmias

Cardiac arrhythmia surgery was initiated in 1968 with the first successful division of an accessory AV connection for the Wolff-Parkinson-White syndrome. Subsequent surgical procedures included the left atrial isolation procedure and right atrial isolation procedure for automatic atrial tachycardias, discrete cryosurgery of the AV node for AV nodal reentrant tachycardia, the atrial transection procedure, the corridor procedure, and the maze procedure for atrial fibrillation, the right ventricular disconnection procedure for arrhythmogenic right ventricular tachycardia, and the encircling endocardial ventriculotomy, subendocardial resection procedure, endocardial cryoablation, the Jatene procedure, and the Dor procedure for ischemic ventricular tachycardia. Because of monumental strides in the treatment of most refractory arrhythmias by endocardial catheter techniques during the past decade, the only remaining viable surgical procedures for cardiac arrhythmias are the maze procedure for atrial fibrillation and the Dor procedure for ischemic ventricular tachycardia. Nevertheless, the 25 to 30 years of intense activity in the field of cardiac arrhythmia surgery provided the essential foundation for the development of these catheter techniques and represent one of the most exciting and productive eras in the history of medicine. In one short professional career, we have witnessed the birth of arrhythmia surgery, its adolescence as an "esoteric" specialty, its prime as an enlightening yet exhausting period, and finally its waning years as a source of knowledge and wisdom upon which better methods of treatment have been founded. One could hardly ask for a more rewarding experience.

Left Atrial Radiofrequency Ablation During Cardiac Surgery in Patients with Atrial Fibrillation

INTRODUCTION

Intraoperative left atrial radiofrequency (RF) ablation recently has been suggested as an effective surgical treatment for atrial fibrillation (AF). The aim of this study was to verify the outcome of this technique in a controlled multicenter trial.

METHODS AND RESULTS

One hundred three consecutive patients (39 men and 65 women; age 62 +/- 11 years) affected by AF underwent cardiac surgery and RF ablation in the left atrium (RF group). The control group consisted of 27 patients (6 men and 21 women; age 64 +/- 7 years) with AF who underwent cardiac surgery during the same period and refused RF ablation. Mitral valve disease was present in 89 (86%) and 25 (92%) patients, respectively (P = NS). RF endocardial ablation was performed in order to obtain isolation of both right and left pulmonary veins, a lesion connecting the previous lines, and a lesion connecting the line encircling the left veins to the mitral annulus. Upon discharge from the hospital, sinus rhythm was present in 65 patients (63%) versus 5 patients (18%) in the control group (P < 0.0001). Mean time of cardiopulmonary bypass was longer in the RF group (148 +/- 50 min vs 117 +/- 30 min, P = 0.013). The complication rate was similar in both groups, but RF ablation-related complications occurred in 4 RF group patients (3.9%). After a mean follow-up of 12.5 +/- 5 months (range 4-24), 83 (81%) of 102 RF group patients were in stable sinus rhythm versus 3 (11%) of 27 in the control group (P < 0.0001). The success rate was similar among the four surgical centers. Atrial contraction was present in 66 (79.5%) of 83 patients in the RF group in sinus rhythm.

CONCLUSION

Endocardial RF left atrial compartmentalization during cardiac surgery is effective in restoring sinus rhythm in many patients. This technique is easy to perform and reproducible. Rare RF ablation-related complications can occur. During follow-up, sinus rhythm persistence is good, and biatrial contraction is preserved in most patients.

Usefulness of a new radiofrequency thermal balloon catheter for pulmonary vein isolation: a new device for treatment of atrial fibrillation

INTRODUCTION

A rapidly firing or triggered ectopic focus located within a pulmonary vein (PV) or close to the PV ostium could induce atrial fibrillation (AF). The aim of this study was to evaluate the efficacy and safety of a radiofrequency thermal balloon catheter for isolation of the PV from the left atrium (LA).

METHODS AND RESULTS

Twenty patients with drug-resistant paroxysmal AF were treated by isolating the superior PVs using an RF thermal balloon catheter. Using a transseptal approach, the balloon, which had an inflated diameter 5 to 10 mm larger than that of the PV ostium, was wedged at the LA-PV junction. It was heated by a very-high-frequency current (13.56 MHZ) applied to the coil electrode inside the balloon for 2 to 3 minutes, and the procedure was repeated up to four times. The balloon center temperature was maintained at 60 degrees to 75 degrees C by regulating generator output. Successful PV isolation was achieved in 19 of the 20 left superior PVs and in all 20 of the right superior PVs and was associated with a decrease in amplitude of the ostial potentials. Total procedure time was 1.8 +/- 0.5 hours, which included 22 +/- 7 minutes of fluoroscopy time. After a follow-up period of 8.1 +/- 0.8 months, 17 patients were free from AF, with 10 not taking any antiarrhythmic drugs and 7 taking the same antiarrhythmic agent as before ablation. Electron beam computed tomography revealed no complications, such as PV stenosis at ablation sites.

CONCLUSION

The PV and its ostial region can be safely and quickly isolated from the LA by circumferential ablation around the PV ostia using a radiofrequency thermal balloon catheter for treatment of AF.

Atrial fibrillation: current surgical options and their assessment

Atrial fibrillation (AF) is the most common cardiac arrhythmia and is associated with morbidity and mortality. Traditional surgical treatment of AF is the Cox-Maze III procedure, a complicated operation. New surgical approaches include alternate energy sources (radiofrequency, microwave, cryothermy) and simplified left atrial lesion sets. These operations cure AF in 70% to 80% of patients. This review describes contemporary and emerging surgical approaches to AF, synthesizes results of these operations, and proposes new standards for reporting results of AF treatment.

Effects of prednisone and ibuprofen on radio frequency volume tissue reduction in a rabbit model

This study investigates whether acute anti-inflammatory medications (prednisone and ibuprofen) alter muscle volumetric reduction following radio frequency tissue ablation (RFTA). We used a rabbit model to measure changes in leg muscle volume using serial magnetic resonance imaging in 3 groups: RFTA without medication (group 1), RFTA with prednisone and ibuprofen (group 2), and no RFTA or medication (group 3). The mean volumetric changes for groups I and 2 differed on days 1 and 7 (+0.5 cm3 versus -0.4 cm3, p < .0001; and -0.03 cm3 versus -0.7 cm3, p < .05), but not on day 28 (-0.8 cm3 versus -1.0 cm3, not significant). Group 3 had no change in volume. The volumetric reduction varied. Impaired volumetric reduction (<50% mean change) occurred in 30% of extremities and correlated to lower tissue impedance (p < .04). Combined steroidal and nonsteroidal anti-inflammatory medications did decrease acute edema, but not the final volumetric reduction, following RFTA. Volumetric changes are variable and may be altered by tissue impedance.

Radiofrequency lesions produced by handheld temperature controlled probes for use in atrial fibrillation surgery

OBJECTIVES

Detailed analysis of the size and shape of lesions produced by handheld radiofrequency ablation devices at open heart surgery has not been reported previously.

METHODS

Radiofrequency lesions were made from the epicardial surface of the cardiac ventricles in open-chested dogs. The effects of electrode size, electrode temperature and duration of ablation were studied. In a second group of experiments simultaneous multielectrode ablation was performed on the ventricular epicardium after cold cardioplegia.

RESULTS

Using a single 12 x 2.5 mm electrode and a target temperature of 80 degrees C the lesion depth increased from 3.8+/-0.9 mm at 15 s, to 6.1+/-0.9 mm at 120 s (P=0.01). Increasing the target temperature from 70 to 90 degrees C (for 60 s) increased lesion depth from 5.0+/-1.2 to 5.6+/-1.7 mm (P=0.2). There was no difference in depth of lesions with the two electrode widths (4.0+/-0.5 mm (large) vs. 3.9+/-1.0 mm (small)). Lesions produced using the multielectrode probe (80 degrees C, 60 s) were 30-35 mm long with even penetration into the tissue. The mean depth of these lesions on microscopic sections was 3.9 mm. The mean width was 7.1 mm.

CONCLUSIONS

Handheld probes can be used to make deep linear lesions in the myocardium. Lesions expand rapidly and are wider than they are deep. A multielectrode ablation device allows rapid formation of linear lesions.

Intraoperative radiofrequency maze ablation for atrial fibrillation: the Berlin modification

BACKGROUND

The Cox-maze procedure combined with an operation for organic heart disease is highly successful in the elimination of chronic atrial fibrillation. However, it prolongs significantly the aortic cross-clamp and operating time. In this study, a simplified left atrial maze procedure, which is a short procedure performed using a surgical radiofrequency ablation probe, is added to elective open heart procedures in patients with atrial fibrillation.

METHODS

Forty-eight adults with atrial fibrillation (duration, 6 months to 36 years) underwent elective open heart operations (isolated valve procedures or coronary artery bypass grafting, n = 27 patients; combined procedures, n = 21 patients) combined with intraoperative radiofrequency ablation of the left atrium. The postoperative follow-up period ranged from 1 to 11 months (mean, 4 months). Possible predictors for persistent postoperative atrial fibrillation were determined among 40 variables by univariate and multivariate analyses.

RESULTS

Intraoperative radiofrequency ablation prolonged the aortic cross-clamp time for 6 to 14 minutes (mean, 11 minutes). Freedom from atrial fibrillation was 100% intraoperatively, 25% at 1 week after operation (12 of 48 patients), 59% at 1 month postoperatively (16 of 27 patients), 64% at 3 months postoperatively (16 of 25 patients), and 92% at 6 months postoperatively (12 of 13 patients). The only predictor of postoperative atrial fibrillation was the presence of coronary artery disease (odds ratio, 7.5; 80% confidence interval, 2.24-25.13).

CONCLUSIONS

Intraoperative radiofrequency ablation of the left atrium combined with an operation for organic heart disease effectively eliminates atrial fibrillation without significant prolongation of the aortic cross-clamp and operative time. The presence of coronary artery disease decreases the success rate during the first 6 postoperative months.

Evaluation and management of atrial fibrillation

Atrial fibrillation is a common cardiac arrhythmia with significant sequela. The goals of treating atrial fibrillation are rate control, prevention of thromboembolism, and maintenance of sinus rhythm. The epidemiology and pathophysiology of atrial fibrillation is reviewed, as well as strategies and recommendations for achieving therapeutic goals. The authors also review investigational therapeutic options using nonpharmacologic modalities.

Cox-Maze procedure for atrial fibrillation: Mayo Clinic experience

The Cox-Maze procedure corrects atrial fibrillation in 90% of patients, and successful operation restores sinus rhythm, thereby reducing risks of thromboembolism and anticoagulant-associated hemorrhage. Symptoms such as palpitation and fatigability also improve with restoration of atrioventricular synchrony. At the Mayo Clinic, 221 Cox-Maze procedures were performed from March 1993 through March 1999. Over 75% of patients had associated cardiac disease and concomitant operations. Overall, early mortality was 1.4%, and the incidence of postoperative pacemaker implantation was 3.2%. Limiting incisions to the right atrium simplifies the operation for patients who primarily have tricuspid valve disease, and in early follow-up, outcome appeared to be as good as that achieved with biatrial incisions. The Cox-Maze procedure has proved particularly useful for patients with preoperative atrial fibrillation who require valvuloplasty for acquired mitral valve regurgitation; 87 patients have had this combined procedure, and there have been no early deaths. Further, our experience indicates that ventricular dysfunction is not a contraindication for operation and that restoration of sinus rhythm after the Cox-Maze procedure improves left ventricular ejection fraction in most patients.